Cerebrovascular responsiveness to hypercapnia in Alzheimer's dementia and vascular dementia of the Binswanger type.

Abstract

Alzheimer's dementia is thought to be a primary degenerative dementia, whereas vascular dementia of the Binswanger type is an entity of vascular dementia. We evaluated the cerebrovascular responsiveness to hypercapnia to clarify the differences in the cerebral hemodynamics between two groups of patients. The subjects were eight younger control subjects, five age-matched control subjects, five Alzheimer's patients, and five patients with vascular dementia of the Binswanger type. In the resting state, the regional cerebral blood flow was low in both Alzheimer's dementia and vascular dementia of the Binswanger type. The responsiveness to hypercapnia was preserved in Alzheimer's dementia, whereas it was impaired in vascular dementia of the Binswanger type in the cerebral cortices and in the deep white matter. These results suggest that small vascular lesions exist in vascular dementia of the Binswanger type but not in Alzheimer's dementia, even though regional cerebral blood flow was thought to decrease by hypometabolism in both types of dementia.